Spain's most notorious bull killing event was held today despite huge protests against the barbaric spectacle.

Thousands of people chased the terrified animal through narrow streets at the Toro de la Vega fiesta before groups of men on horseback slowly stabbed it to death with long spears.

Activists were attacked as they tried to film the death of this year’s bull after it was tormented through the town of Tordesillas in northern Spain, a town of 9,000 inhabitants known to be fiercely defensive of their annual bull killing.

Campaigners claim the bull - called Rompesuelas - was attacked by spearmen hiding behind trees and from outside the boundaries of the valley - breaking the strict rules of the event.

Covert camera footage of the animal’s final moments sees the exhausted animal surrounded by a crowd before being lanced in his side and slumping to the ground.

Claire Bass, UK director for Humane Society International, said: “In common with the vast majority of Spanish citizens we are sickened by the gratuitous animal cruelty that took place at today’s Toro de la Vega fiesta.

“Rompesuelas the bull endured a terrifying and protracted ordeal for the entertainment of the crowd before being killed.

“It’s time for Spanish politicians to wake up to 21st century ethical values and end this barbaric, archaic and perverse form of ‘entertainment’ for good.”The bull run started from the north of the medievial town in the province of Valladolid, 120 miles north of Madrid.

They chase the frightened animal through the town, crossing the bridge of the River Duero out into open fields where lancers and horsemen await.

All comers battle for the honour of killing the animal out in the open plain.

The winner of the tournament trophy is the one who lands the mortal wound on the bull bringing it to its knees, before an accredited expert deals the final blow to the animal’s neck.

The local authority which governs the event was reportedly investigating yesterday whether rules governing where the bull can be killed and how many people can deliver the final blow were broken.

In previous years protesters have clashed with heavily armed bull runners.

Protest: Animal-rights activists (r) show their disdain for the event (Image: Getty)

The Animalist Party, known as PACMA in Spain, who filmed the footage said in a statement: “Rompesuelas had been lanced repeatedly, even by lancers hiding behind trees and spearmen outside the boundaries of the valley, breaking the rules of the celebration itself.

“PACMA denounce these irregularities, in order to serve to end this event by legal means," the statement continued.

“The camera sent by the Animalist Party have been attacked. However PACMA has achieved images of the terrible death of Rompesuelas."